# Appendix Physical Chemistry

## Physical Quantities:

In physical science, we commonly deal with quantities such as pressure, volume, mass, temperature, current, etc. These quantities are known as physical quantities.
A physical quantity has two components, namely, numerical value and its unit and is written as,
 Physical quantity = Numerical value unit
 Force = 5 Newton
Here Physical quantity Newton and its numerical value 5
 Physical quantity Name of the Unit Symbol Length Centimeter cm Mass Gram gm Time Second S Electric Current Ampere Amp Temperature Kelvin 0K
 Physical quantity Name of the Unit Symbol Length Meter m Mass Kilogram Kg Time Second S Electric Current Ampere Amp Temperature Kelvin 0K
 Physical quantity Name of the Unit Length L Mass M Time T

### Definition of Seven Base Physical Quantities:

Metre: The metre is the length of path traveled by light in vacuum during a time interval 1/299 792 458 of a second.
 1. Area
Area = Length × Length
Thus the unit of Area = Unit of Length × Unit of Length
Unit of Area in C.G.S. System = cm × cm = cm²
Unit of Area in S.I. System is = m × m =
Dimension of Area = L × L = [L]²
 2. Volume
Volume (V) = Length × Length × Length.
Thus the unit of Volume = Unit of Length × Unit of Length × Unit of Length.
Unit of Area in C.G.S. System = cm × cm × cm = cm³
Unit of Area in S.I. System is = m × m × m = m³
Dimension of Area = L × L × L = [L³]
 3. Density
Density (d) = Mass/Volume
Thus the unit of Area = Unit of Mass/Unit of Volume.
Unit of Area in C.G.S. System = gm/cm³ = gm cm⁻³
Unit of Area in S.I. System is = Kg/ = Kg m⁻³
Dimension of Area = [M]/[L³] = [M L⁻³]
 4. Force
From the Newton Second Low of MotionForce = Mass × Acceleration.
or, Force = Mass × Velocity/Time
or, Force = Mass × (Length/Time) /Time,
Here Velocity = Length/Time
or, Force = Mass × (Length/Time²)
Thus the unit of Force in C.G.S. System, =Unit of Mass × (Unit of Length/Unit of Time²)
= gm × cm/sec2
gm cm/sec2
or, gm cm sec-2
or Dyne.
Again in the same way Unit of Force in S.I System,
Kg m/sec2
or Kg m sec-2
or Newton.
From the above discussion dimension of Force, = dimension of Mass × dimension of Length/dimension of Time².
Thus the dimension of Force = [MLT-2]
 Conversation Newton to Dyne
1 Newton = Kg m/sec2
= (1 Kg× 1 m )/(1 sec)²
We know that, 1 Kg = 10³ gm and 1 m = 10² cm
Thus, 1 Newton = (10³gm × 10² cm)/(1 sec)²
= 10⁵ gm cm/sec2
105 Dyne
 5. Work
We Know that, Work (W) = Force(F) × Displacement(d).
Thus, the unit Work = unit of Force × unit of Displacement(d)
∴ Unit of Work in C.G.S. System, = (gm cm/sec2) × cm
or, gm cm2/sec2
or, gm cm2sec-2
or, erg.
And unit of work in S.I. system = (Kg m/sec2) × m
or, Kg m2/sec2
Kg m2sec-2
or, Joule.
From the above discussion dimension of Work, = dimension of Mass × {(dimension of Length)²/dimension of Time²}.
Thus dimension of Work = [ML2T-2]
 Conversation Joule to erg
1 Joule = 1 Kg m²/sec²
= (1 Kg × 1 m² )/1 sec².
We know that, 1 Kg = 10³ gm and 1 m = 10² cm.
Thus, 1 Joule = {10³ gm × (10²)² cm}/1 sec²
= 10⁷ gram cm²/sec²
= 10⁷ erg.
 6. Work
The ability to doing work is termed as Energy. Thus, the unit and dimension of energy and work is same.
Unit of Energy in C.G.S System is erg and S.I. System is Joule.

Physical Quantities C.G.S. Units S.I. Units Dimension of Physical Quantity Derived Units and Dimension From its Basic Formula Force Conservation of 1 Newton to 1 Dyne Work Conservation of 1 Joule to 1 erg

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